Historically, wireless networks have been used as a last-hop connection technology, where the wireless device communicates with another device that is connected to a high-rate wired connection. This wired-to-wireless interface is commonly found in cellular and wireless local area network (WLAN) applications. Despite the enormous amount of research focused on multi-hop wireless networks, the commercial applications have been limited.
The increasing numbers of wireless connected devices and access points are altering this model. Many of these devices will be low-power and low-complexity Internet of Things (IoT) devices. Due to the low transmit powers of these nodes, a large fraction of the deployed IoT devices will not have any single-hop connection to a base station or access point. Multi-hop deployments will be critical to facilitating many of the proposed IoT applications.
Simultaneously, cellular systems, primarily deployed using 3GPP technical standards such as LTE and LTE-Advanced, are moving towards small cell models. Traditional fiber or copper backhaul networks cannot scale to meet the complexity of these complicated small cell deployments. Self-backhauling, where a fraction of the carrier's bandwidth is set aside for backhaul communication, is starting to dominate future deployment discussions. Though not generally thought of as multihop framework, self-backhauling systems clearly fall inside the academic multihop paradigm.
These commercial multihop deployments are further complicated by the growing focus on latency. 5G systems have a goal of a 10× latency improvement over 4G systems. When these low-latency requirements are combined with any self-backhaul or IoT scenarios, the results are troubling. This is primarily because the design of standardized systems focuses on long blocklengths, which are decoded and reencoded at intermediate nodes.
This new research area is best practically illustrated by 3GPP's recent focus on Integrated Access and Backhaul (see 3GPP TDoc RP-17148). This recently proposed study item aims to address multiple 5G requirements including that the network “shall support multi-hop wireless self-backhauling . . . to enable flexible extension of range and coverage area”, “shall support autonomous adaptation on wireless self-backhaul network topologies to minimize service disruptions”, and “shall support topologically redundant connectivity on the wireless self-backhaul . . . enhance reliability and capacity and reduce latency”.
The challenge of multihop communication with tight latency and/or computational constraints is of immediate commercial and academic interest. Finite blocklength information theoretic analysis has only recently become an area of emphasis within the research community. Instead of proposing a new ad-hoc design for specific applications, a general framework is needed.
Similar problems also arise in wired networks. Heterogeneous wired networks are commonly found. An example is a high-rate fiber line being interfaced to an Ethernet network, and such a wired multihop scenario faces the same challenges as the wireless counterpart, i.e., how to design low-latency high-throughput schemes. Therefore, improvements are needed in the field.
To address these, and other shortcomings of existing relaying and multi-hop techniques, the present disclosure provides a comprehensive technique referred to herein as “transcoding” which can improve throughput, reduce latency, and decrease computational demands at intermediate nodes.